Error while using chooser/saver: "Uh oh! Seems like this widget is not configured properly...."

Question

I am trying demo for chooser/saver demo at https://codepen.io/gauravsc/pen/dqRGjv I am getting error "Uh oh! Seems like this widget is not configured properly. Origin does not match any app domain". I have added www.codepen.io in Chooser/Saver domains in app settings. Below is my code. I am getting error at both Chooser/Saver.

Dropbox Chooser/Saver Demo

Greg-DB · Accepted Answer

It looks like CodePen serves on just codepen.io, not www.codepen.io, so you need to register codepen.io (without the 'www') for your app's 'Chooser/Saver domains' 
on the app's page on the App Console.